Despite clear benefits, the use of methadone during pregnancy is controversial partly due to a high incidence of neonatal abstinence syndrome (NAS) requiring medical intervention and extended hospitalization. A newly approved medication, Buprenorphine, produces only a mild abstinence syndrome following abrupt withdrawal. Promising preliminary data from a double-blind randomized trial at the Johns Hopkins School of Medicine (JHUSOM) suggest that buprenorphine use results in improved birth outcomes and less NAS relative to methadone. The current randomized, parallel group study will be the first multi-site trial to assess the efficacy of buprenorphine for reducing NAS relative to methadone. St. Joseph's Health Centre (SJHC) proposes to participate in the multi-site trial lead by JHUSOM involving six U.S. and two international sites. SJHC has brought together a multi-disciplinary group trained in addiction medicine, psychiatry, toxicology, pediatrics, obstetrics, neonatology, and controlled clinical trials with the professional expertise to provide comprehensive care for the subjects and rigorous scientific integrity for the study. At this site, subjects randomized to equivalent optimal doses of methadone (n=15) or buprenorphine (n=15) will be followed through pregnancy. Treatment groups will be compared on the primary outcome measures of peak total NAS score; number of neonates treated for NAS; total amount of anti-withdrawal medication given to neonates treated for NAS; physical birth parameter of head circumference; and neonatal length of hospital stay. Secondary neonatal/fetal outcome measures include other physical, behavioral and safety parameters. Secondary maternal outcomes include treatment retention, drug use, medication safety, psychosocial functioning and dose adequacy. Unique to this site, is the extended follow-up of both neonates and mothers for 6 months. This study will provide pivotal data on the optimal management of pregnant opioid dependent women and establish a network for future studies with this population.